Indicating system



p 1943- v. A. JOHNSON 2,330,358

INDICATING SYSTEM Filed May 1 1941 7 Sheets-Sheet l clalZ Ecnao FIG.FIG. FIG. 2 l- 5 1 7 6 5 CB2] FIG FIG FIG. FIG 2 3 4 us o 0133; l .1

C1341 L120 Cl35 V LINE SWITCH 0 I044 I OT/1,08 1'09 MASTER, SWITCHTIMING DEVICE STATION A INVENTOR. VINCENT A.JOHNSON BY M,d:v14a:7,M M

AfToR Exs v v. A. JOHNSON 2,330,358

INDICATING SYSTEM Filed May 1, 1941 'T Sheets-Sheet 2 Sept. 28, 1943.

GONTROL NETWORK I6 zes START SEND an H LINE I R220 ,i 282 R260 -R-270R280 R290 R295 -zee INVENTOR. vmcem A.JOHNSON ,omd m m ATTORNEYS LEASERZIO Sept. 28, 1943. v. A. JOHNSON INDICATING SYSTEM Filed May 1, 1941 7Sheets-Sheet 6 AUTOMATKZ PULSE SENDER 15 M. o m w a Gr mm 06 HR SAN vGTE RS5 A: o m a M M NWLL e R 7 W h? m QT a V 6 5 W. F-

4 F. 3 aw e m a wJ... M 0 a .V P T 2 v 1% in. m r a R l 2 E I am 2 a l aU. OT. o l 5 ..IR l a g 6 OR 4 l 6 o 6 2 s E 1 w 2 f 5 r 0 \l -4 T B 1mm m m; m a w w M mm a c m m m INVENTOR. VINCENT A.JOHNSON MX m MATTORNEYS Sept. 28, 1943. v. A. JOHNSON INDICATING SYSTEM Filed May 1,1941 7 Sheets-Sheet 7 I "I I" l '4 7' I'll a ill")! INVENTOR. VENCENTA.JOHNSON BY m i I v ATTORNEYS Patented Sept. 28, 1943 UNITED STATES Ammoa'rmo Vincent A. Johnson, Evanston, Ill; assignor to AutomaticElectric'Laboratoi'ies, Inc,- a corporation of Delaware Application May1, 1941,1Serial No. 391,275 7 14 Claims. (01.- 177-353) The presentinvention relates to systemsfor indicating the location of one or morepersons or objects which may be located in different zones of apluralzone area, and more particularly to improvements in systems forproviding accurate information as to the whereabouts of a large numberof doctors who may be working on the different floors of a largehospital. An improved system of this character is disclosed and claimedin the co-pending application Serial No. 390,557 filed April 26, 1941,Thomas H. Mote, which is assigned to the same assignee as the presentinvention, and the present invention relates to improvements thereover.In the system disclosed in the Mote application, a display board isprovided on each floor of the hospital and each board includes. signalcontrolled indicators arranged in sets which are individual to thevarious doctors. These indicators are selectively controllable throughautomatic switching equipment from control stations conveniently locatedon the floors of the hospital, and ,function to indicate the floorswhere the respective, corresponding doctors may be located. Theindicators are of the pulsecontrolled type, each thereof including anindicator drum which may be driven from any offnormal position to itsblank position .whena train of ten restoring pulses is transmitted tothe associated operating magnet, and may be advanced from the blankposition to any desired oil-normal or display position when apredetermined train of reset pulses is transmitted to the associatedoperating magnet. In the Mote system, selector and connector switchesare utilized in selecting the indicators individual to any doctor. Theseswitches are controlled through the operation of the dial-operated"impulse senders provided at the control stations'of the system. Onlythe selection of the sets of indicators individual to the desireddoctors is accomplished through operation of the impulse sendingdevices, the transmission of the restoring and reset pulse trains to theselected indicators being accomplished through the operation ofautomatic signal or pulse senders individual to the various zones orfloors of the hospital. Although the system is simple in arrangement,fully satisfactory in operation,- and includesseveralimproved and noveloperating features, it requires anautomatic signal or pulse sender foreach zone or floor of the hospital in which a control station islocated.

It is an object of the present invention, therefore; to provide animproved systemof the character described which issimple in arrangement;s5

which includes provisions whereby any person instituting a change -inthe setting 0f certain se lected indicators, is automatically informedas to the progress of the cont .ol connectionwhich is setup toeffect thedesired indicator change.

; It is still another object -of theinvention to provide in a system ofthe character described, facilities whereby ,a-delayinterval, separating the selection of a setof indicators frornl-theresetting of; theelected indicators, is introduced-in the operation of the apparatus-1x1order that the user of the'system may release-the ccntrol connectionthrough whichthe indicators are selected withoutdisturbing the settingof the selected indisetofindicators has been selected, n e V Itis stillanother object of the invention .to pro- ,vide an improved system of thecharacter-dc .scribed which includes provisions for automati- .cal y rela naa a oma b-ins equipr ment which is held from anyof the controlstations-of the system for an unreasonabletime i te va I caters intheeventit is discovered that the wrong In the illustrated embodimentofthe; invention V .theset ofindicators-individual to each doctor afloe se dito n we th nt stai- :tio s y d a nsijf f". an 1 ide tifi ation.inumbers whi ha in iv d a s en c p the docto Th cd alins of hes num ersse v :t 11 1 10 h v d recti s ont o d e cter n connector switches sothat acontrol connectionis set up-toth desired set of indicators. Theautomatic signalsericlers, provided for transmitting the restoring andreset pulse trains .tose- --lected onesofthe indicators, areindividualto the selector. switches, and each thereof is opera- ..tivelyassociated with a selected .set cfindicat rs when a control-connectionisfiet 1 p thrpugh'the ,associatedselector switch and one of ,-the, connector switches to theselected indicators. Incident to the -.completionof I this control connec .tion; the operation oflthe seized signalsender is initiated to transmit to the selectedfindicators' a ifrain, ofrestorin g pulses followed by trains ENT rel-CE f.

' group and "play unit 21 2 of reset pulses which indicate by thenumerical values thereof the zone or floor from which the selectedindicators are being controlled. In order that the trains of resetpulses may accurately indicate the zone of the calling control station,unit marking paths individual to the various control stations are set upto each sender when the sender is seized. These paths serve to determinethe number of pulses of each of the two reset pulse trains in accordancewith the zone of the calling control station.

In accordance with another feature of the pres- I ent invention, eachcontrol station is equipped with signaling means in the form of a pilotlamp, and provisions are made in matically controlling this lamp toproduce diiferent signal indications as a control connection isprogressively extended through difierent ones of the automatic switchingstages to a desired set of indicators. More specifically, this lamp, asprovided at each station, is controlled to indicate an all-switch-busycondition at any switching stage, and to provide an indication as towhen the' dialing operation may be started and when the desired set ofindicators has been selected. In accordance with another feature of theinvention, two sets of timing equipment are incorporated in the system,which have distinctly dif ferent functions, although the operationsthereof are correlated. 'More specifically, each selector switch isequipped with apparatus which responds tothe operation of one set oftiming equipment by automatically releasing the selector switch in theevent a control connection, as routed to the switch from one of thecontrol stations, is not extended through the switch to a desired set ofindicators within a predetermined time interval. The timing devices ofthe other type are individual to the various selector switches and-eachthereof functions to delay the operation of an associated signal senderfor a measured time interval which starts'with the selection of thedesired setof indicators.

The novel features believed to be characteristic of the invention areset forth with particularity in the appended claims. The invention, bothas to its organization and method of operation,

together with-further objects and advantages thereof, will best beunderstood'by reference to the specification taken in connection withthe accompanying drawings in which Figs. 1, 2, 3, 4, 5, 6 and 7 whencombined in the manner shown in Fig. 8, illustrate a portion of theequipment provided in a system which includes the features ofthe'invention briefly outlined above.

' Referring now more particularly to the drawingsfthe system thereillustrated comprises a plurality of display boards which are individualto the various floors of the hospital and each of which is convenientlylocated for easy observation from any point in the corridor of the'flooron which it' is located; One such display board is indicated at [asbeing provided on the first floor of the hospital. This display boardcomprises a plurality of display units 25, 21, 28, 29, 30, etc. whichindividually correspond to the doctors whose locations are to be postedon the board. For example, the display unit 26 may be utilized toindicate the location of the doctor who is assigned the inidentification number 247 and. the out identification-number 147,- andthe dismay be utilized to indicate the location' of the doctor who isassigned the in idenftification number 257 and the out identificationnumber 157.

The various display boards the system for auto- 11, 1941, to Haroldcontrol stations in the hospital.

are of identical arrangement and, as will appear more fully hereinafter,are so arranged that the corresponding indicators of each display unitor indicator set are controlled in unison. The individual display unitsof the display boards are also identical in arrangement, the illustratedunit 26 comprising a pair of floor indicating display registers orindicators 500a and 50 3b. These registers are of the well-knownelectromechanical type and each thereof is provided with a display drumwhich may be rotated from a normal or blank position to any one of tenoff-normal positions wherein the numerals one to nine and zero arerespectively displayed thereby. If desired these registers may be of theform disclosed in Fig. 22 of Patent No. 2,234,684, granted March C.Robinson and Martin L. Nelson. More specifically, the register 500a isprovided to display the tens digit of any floor number from ten toninety-nine, and the register 50% is provided'to display the units digitof such floor numbers. The indicating drum of each display register 500is mounted on a drive shaft, to which rotary movement is imparted in onedirection only'by an associated signal-controlled operating magnet EDIthrough an associated ratchet and pawl or Geneva gear mechanism, notshown. The drive shaft of each indicator also carries a cam 584 which isarranged to control two associated sets of commutating contacts 502 and503, in the manner more fully explained hereinafter.

The control of the various display boards is effected from controlstations which are conveniently located in each zone or on each floor ofthe hospital. Thus the nineteenth floor of the-building is provided witha control station A, which includes a signal transmitting device lOIa, acombined call and release key IBM, and a pilot lamp [8511. The connectkey "14a is of the wellknown non-locking type, and is provided with acall position and a release position in addition to its normal position.The signal transmitting device lflla is of the well-known dial-operatedtype conventionally used in substations of automatic telephone systems.More specifically, this signal transmitting device includes a set ofpulsilng springs "32a and a set of off-normal springs 03a.

The selection and selective control of the indicators included in thevarious display units of the display boards are effected through theprovision of automatic switching equipment, the major portion of whichis common to all of the More specifically, this equipment includes lineswitches individual to the 'various floors of the hospital and havingaccess to a group of selector switches, which selector switches, inturn, have access to five groups of connector switches through which thevarious display units may selectively be seized for control purposes. Inthe drawings only a single lineswitch H, individual to the controlstation onrthe nineteenth floor, a single selector switch [2,.and asingle connector switch [3 are illustrated. Each connector switch ofeach group -has access to the display units individual to one hundreddoctors and, since five groups of connector switches are provided, thetotal posting capacity of the illustrated system is five hundreddoctors. It will be understood, however, that by providing additionalswitching stages the capacity of the system may be expanded as desired.For

example, if second selector switches are interposed between the firstselector-switches and the connector switches, andadditional-g'roups ofconnector switchesare'provided, the system capacity may be increased tofive thousand doctors;

I The various lineswitches individualit'o therseveral floors are of thewell-known'plunger type, a master switch Ill of conventional,arrangement being provided for controlling the operating plungers ofthese switches so that-they are always. positioned opposite a set ofcontacts terminating a trunk extending to an idle firstselector. Brieflydescribed, the line switch I lincludesa bank. of contacts, theindividual contacts of which are arranged in horizontal rows. The

vertically aligned contacts of the various-rows constitute contact setsat which the conductors of the :trunks extending to the various'first'sclectors are terminated. In the illustrated an rangement, each contactset includes four pairs of contact springs. For the purpose of actuatingthe operating plunger of the :switch .to actuate the contacts of aselected set into engagement, the usual. operating assembly is providedwhich includes a bridge cut-off armature ill, a plunger armature I l2,and a double-wound operatingmagnet H9. The switch. also includes a linerelay R100 which, in accordance with. conventional practice, is' of theslow-to-operate type.

As indicated above, the switch plunger is,auto-. m-atically maintained.in a position oppositela. set of contacts terminating the conductors ofa trunk extendingto an idle selector, through operation of. the masterswitch Him a manner well understood in the art. More specifically, thismaster switch operates to search for. an idle. selector switch .eachtime a previously selectedselector switch is seized through one of theline switches. Incident to the searching. operation, .the plungeroperating sector of the master .switch is so operated that, as each,trunk is tested, the line switch plungers. are positioned oppositethe-con.- tacts terminating the conductors of, thetested trunk.Accordingly, when an idle trunk is found to arrest the searchingoperation of the master switch, the plungers of the various lineswitches are positioned .opposite the contacts terminating theconductors of the selected idle trunk. For the purpose of preventinguseless searching on the part of the master switch It at a time when allof the selector switches are in use, busy relays R310, R312, R314, R315,R373, etc. individual .to. the various selector switches, are provided.These relays are arranged to control a. chain circult. which, whencompleted, serves to energize an all-switch-busy relay in the masterswitch If]. The latter relay, in operating, functions to prevent thecontinued operation of the masterswitch equipment. 7 i

Each of the selector and connector switches of theJsystem includes atwo-motion switching mech-. anism of the well-known ,Strowger type. Eachswitching-mechanism is equipped with a plurality of banks of contactseach including one hundred "contact points. each contact field aredivided intoten levels (of ten-contact sets each, and each ofthebankshas associated therewith a wiper which is carried by an associatedvwiper carriage structure. of wellknown construction and arrangement.Thus the selector switch l2 isJillustrated in FiguS'OfJthE drawings ascomprising acontact field divided into four banks having the wipers 368,!,3362 and-.36.3 individually associated therewith: .The trunksextending to "the connector. switches-rac ce'ssible to the selectorswitch t2. are :each :ter

The. contacts making'up net 485 is provided. The minor switch furtherminated at two sets. of contacts: inadja'cnt lei' els oi" the selectorswitch; Thus the trunk- [8 ex: tending to the connector switch [3ismultiple'd to the corresponding contact sets of thefifirst' and secondlevels of the contact fieldembodied in the selector switch F2. Thepurpose of this arrangement is to permit any doctor selectively to wipeout. indications displayed by the indicators providedxfor his use, or toreset theseindicatorsto display new indications, bydi'aling' either-J ofhis two identificationnumberseat any one of the control station-5. Themanner in which this is. ac' complished is more fully considered in thefol lowing-detailed descriptionof the operation of the system. .For the:purpose of elevatingl the enumerated wipers of the selectcr'switch l2toaa position opposite a desired levelsof bank contacts;

and then rotating the: same into engagement? with a selected set ofcontacts. of, the selected level; vertical androtarymagnetstfiland 365are included in the switching mechanism. The mechanism' furthercomprises. a release magnet 366 which, when energized, permits" thewiper carriage structure to be returned to rotary. andver= ticalnormal;three sets ofoff-normal springsr361, 388' and 368' which are operated.when the wiper carriage structure is. moved to any vertical offnormalposition; cam-springs: 363 which. are; op erated. into engagement whenthe enumerated wipers are rotated eleven stepsfrom the-rotary. normalposition thereof; and normal post: springs 3635 which are normallydisengaged-andare-moved into. engagement when the wipers 36fi-to. 363-,in-- clusive, are elevated to a; position opposite-any odd-numberedlevel of. bank contacts. The.:operation of the magnets. 355;.335'8J1d356" iscon'-: trolled by a set of control. relays which includes a busysignal relay, R306, alinerelay R3 I ll, .a hold relay R328, a transferrelayRfitUga line switche, ing relay R340, and aitrunk-hunting relayR350: It will be recognized that the-two relays R326] and R33!) are ofthe well-known slow-actingtype:

The Strowger switching;v mechanism. incorpo 1 rated in the connectorswitch. l3 includes three wipers 4H,. l12and 413,.individual'tothe-three banks of the associated contact field, a vertical magnet 414,a rotary magnet 415, a release mag.-: net 415, and two sets of verticaloff-normal springs 41! and 418. The control equipment of this connectorswitch includes a minori'switch 4st and a relay network which comprisesa su-- pervisory relay R409, alinerelay RMO; a slowacting hold relayR429, a slow-acting transfer control relay R430, a. slow-to-releasetransfer: control relay R435; a. pulsing relay R440, andr'a, pair ofpulse circuit transfer relays RAEd-a'n'd R460. The minorswitch 480 is-ofwell-known construction and". arrangement and includes in ner andoutercontact-rows48l andI682'which: are arranged to'bebridged by a wiper 483.An" operating magnet 484' is incorporated in the switch foractuating-the wiperz ifllstepby step over the. contact's of the twocontact rows 481 and';482.- For thepurpose ofrestoringthis wiper to itsillustrated normal position, a release magincludes two sets ofoiT-normal'springs 486 and 487which function to perform controloperations I fully described hereinafter.

"As indicated by the above: description, the *se-- lector and connectorswitches of the system are directively controlled through'operation ofthe-- signal transmitting devices provided at the -variouscontrolstations to select the indicators indi vidualto thevarious-doctors.- The actual con trol of the selected indicators toeffect a change in the indications displayed thereby is efiected throughthe operation of automatic plural digit signal senders which areindividual to the various selector switches. One such signal sender I isillustrated in Figs. 6 and '1 of the drawings as being associated withthe selector switch I2. Briefly described, this sender comprises a pulsecounting network 3|, a set of pulse generating relays R6I5, R620 andR630, and a plurality of auxiliary control relays. The counting network3I includes a pulse circuit transfer relay R100, five counting relaysR1I0, R120, R130, R140 and R150, a reflexing relay R160 and a transferrelay R110. The auxiliary relay equipment of the sender includes a stoprelay R180, a pair of digits spacing control relays R190 and R600, apulse circuit control relay R6I0, a transfer relay R640, a sender startrelay R650, a start sending relay R660 and a slow-acting hold relayR680.

For the purpose of initiating the operation of the pulse sender I5, andof controlling the operation of this sender in accordance with the fioornumber of the control station from which the selector switch I2 isseized, a control network I6 is provided which is individual to thesender I5 and the selector switch I2. Similar networks are provided inassociation with the other selector switches of the system. In thisregard, it is noted that the pulse sender I5 is common to all of thecontrol stations of the system. Accordingly, provisions must be made forcontrolling the reset pulse transmission in accordance with the numberidentifying the floor from which the selector switch I2 and the senderI5 are seized. For example, if a selected set of indicators is to bereset from the control station A located on the nineteenth floor of thehospital, the signal transmitted from the signal sender in use, mustcomprise a first signal digit of one impulse and a second signal digitof nine impulses, in order that the proper indication will be set up bythe selected indicator. To this end, group and unit marking paths areprovided which extend from the banks of the various line switchesthrough contacts controlled by the relays of the control network I6 andthe relays of the counting network 3I to the stop relay R180. Similarmark.- ing paths, also controlled by the relays of the networks I6, 3i,etc., extend to the bank contacts of each of the other line switches ofthe system. These group and unit marking paths serve to determine thenumerical values of the digits transmitted by the sender I5 and theother senders, in the manner more fully explained hereinafter.

Briefly described, the control network I6 comprises a group markingrelay R200, a unit marking relay R2I0, a line relay R220, a slow-actingrelease relay R230, a second release relay R240, a timing relay R250, astart sending relay R260 and four digit transfer relays R210, R280, R290and R235. For the purpose of controlling the release relay R230 of thenetwork I6 and the corresponding relays of the other similarcontrolnetworks, a timing device I1 of conventional ar rangement isprovided. a

Current for energizing the indicator operating magnets, the controlrelays, the pilot lamps, the operating magnets of the various minorswitches, and the operating magnets of the Strowger switchingmechanisms, is supplied from a common direct current source, thepositive terminal of which is connected to acommon bus conductor and toground. The negative terminal ,of the source is connected to a commonnegative bus conductor which terminates the various relay, magnet andlamp terminals identified in the drawings by the negative polarity sign.For convenience in describing the circuits involved, this source ofcurrent, which may conventionally comprise a storage battery floatedacross the terminals of a charging rectifier, has not been shown.

In considering the operation of the system, it may first be assumed thatthe doctor who is assigned the in identification number 247 enters thehospital and proceeds to the nineteenth floor, where he will be occupiedfor a considerable period of time. If this doctor desires to placehimself on call, he may do so by actuating the transmitting deviceprovided at the control station A on the nineteenth floor to transmitthe three digits of his in" identification number to the automaticswitching equipment. Before starting the dialing operation, the doctoractuates the key I04a to its call position, thereby to move the contactsI09 into engagement. Atthese contacts, a circuit including the contactsH3 is completed for energizing the line relay.

RI00 of the line switch II. When energized in this circuit the relayRI00 operates after an interval, and closes its contacts I02 to connectthe contact spring I20 to ground. At its contacts IOI, the relay RI00opens a point in one of the circuits for energizing the upper or BOOwind-. ing of the magnet IIO. At its contacts I04, the relay RI00 opensa point in the in-out chain circuit over which the PDC windings of theoperating magnets in the various line switches may be energized underthe control of the master switch I0. At its contacts I03, the relay RI00prepares a circuit for energizing the PDC winding of the magnet IIO. Ashort time interval after the last-mentioned circuit is prepared, thedelay relay of the master switch I0 functions. to complete the circuit.When thus energized, the magnet H0 actuates its armatures III and H2 topull the associated plunger into the contact bank. Assuming that theselector switch I2 is the switch previously selected by the masterswitch I0, the plunger of the line switch causes the contact springs II1to I20, inclusive, to be moved into engagement with the contact springsterminating the conductors of the trunk extending to this selectorswitch. When the contact spring I20 is moved to engage the contactterminating the conductor CI35, a circuit is completed for energizingthe line relay R220, this circuit extending from ground by way of thecontacts I02, the contact spring I20, CI35, the contacts 24I and 262,and the lower winding of R220 to battery. In operating, the relay R220closes its contacts 22I to prepare the operating circuit for the releaserelay R230. At its contacts 222, the relay R220 prepares the operatingcircuit for the timing relay R250. At its contacts 223, the relay R220opens a point in the operating circuit for the release relay R240. Atits contacts 220, the relay R220 prepares locking circuits for the tworelays R230 and R240. At its contacts 225, the relayR220 completes anobvious path for impressing ground potential upon the timer start leadC226, whereby operation of the timing device I1 is initiated in theevent this device is not already in operation. 'In operating, the linearmature II2 of the ,lin switch II closes its associated contacts II5 tocomplete a circuit for energizing the B00 windengaged to open anotherpoint in ing of the magnet l-lail this circuit extending from ground byway of the contacts I02 'and H5 and the upper or BCO winding of themagnet I I to battery. The energization of this winding serves to retainthe operated armatures III and H2 in their attracted positions after thePDC or lower winding of the magnet II!) is deenergized, in the mannerexplained below. At the contacts I I5, a path including the contacts I02and the contact spring I20 is also completed for impressing groundpotential upon the test conductor CI35 of the trunk extending to theselector switch I 2, whereby thisselector switch is marked as busy inthe master switch I9. In attracting its ECO armature III, the magnetIIII closes the contacts IM to prepare a circuit for energizing thepilot lamp 15a. In attracting its BCO armature III, the magnet Iii alsoopens its contacts H3 to deenergize the line relay RIM.

When the line switch II 'isoperated to seize the selector switch I2 inthe manner just eX- plained, a circuit is completed for energizing thepilot lamp Ififia in series with the line relay R3) of the-selector I2This circuit extends from ground by way of the pulsing springs 12a, theshunt springs 33a, the resistor "16a and the lamp I 65a in parallel, thecontact springs I08, the contact spring II9, C'I34l, the contacts 265and 242, G201, the contacts 344 and the winding of R3!!! to battery.When energized in this circuit, the pilot lamp I05ais illuminated andthe relay R3! operates. The illumination of the lamp a serves to informthe calling doctor that the key IMa may be released. Incidentto therelease of this key, the contacts I09 are disthe operating circuit forthe line relayfRIM.

The relay R3), in operating, closes its contacts 35 I to prepare a pathforexcluding its own winding from the circuit for energizing the pilotlamp 15a. At its contacts 3| 2, the relay R3) completes a circuitincluding the contacts 346 and the ofi-normal springs 368 for energizingthe lower winding of the transfer relay R330. At its contacts 3I3, therelay R3I0 opens a point in the circuit for energizing the verticalmagnet 384 and the upper winding of the relay R330 in parallel. Therelay R330, in operating, closes its contacts 332 to prepare thelast-mentioned circuit. At its contacts 333, the relay R330 prepares theoperating circuit for the trunk hunting relay R350. At itscontacts 334,the relay R330 opens a point in the operating circuit for the rotarymagnet 355. At its contacts 33L the relay R330 completes the preparedoperating circuit for the hold relay R320, this circuit extending toground over a path including the contacts 342 and 345. I

The relay R320, upon operating, locks to round over a path including'thecontacts 322, 3!? and 3%. At its contacts 323, the relay R320 furtherprepares the circuit for energizing the vertical magnet 364 in parallelwith the upper winding of the transfer relay R330. At its contests 32 3,the relay R320 opens a point in the operating circuit for the releasemagnet 366. At its contacts 32L the relayRSZil completes an alternativepath for impressing ground potential upon the test conductor CI35 and,in so doing, closes a locking circuit for the B00 winding of the magnetIIII. This circuit extends from ground by way of the contacts SZLYCZOB,the contacts 24!,the test conductor CI35, the contact spring I29, thecontacts I I5, and the upper contacts I02 to interrupt the initiallytraced circuit fcr energizing the ECG winding of the magnet! Ill. At itscontacts IN, the relay RIM closes an obvious shunt across the contacts vI I5.

At its contacts we, therelayRIIN-interrupts the above described circuitfor energizing the PDC winding of the magnet I I0. At its contacts I04,the relay EH30 recornpletes the in-out chain circuitwhich iscommon tothe line switches and is controlled hy the masterswitch Ill.

, When the test conductor. CI 35 individual to the selector switch I2 isconnected to ground to render this selector switch busy, in the mannerexplained above, the master switch I0 operates in a well-known manner toline up the plungers of all idle line switches controlled by the masterswitch III with the contactswhich terminate the trunk conductorsextending to the next'available free trunk. Thus another of the selectorswitches is preselected by the master switch I!) for'use'in handling thenext initiated call. Inthe event all of the other selector switchesaccessible to the line switches are busy at the time the selector switchI2 is taken for use, in the manner just explained, all of the relaysR310, R312, R314, R315, R318, etc. are operated so that the previouslymentioned chain circuit is completed'for energizing the all-husy relayof the master switch III. This circuit includes the two conductors CI 30and CI3I and the chain-connected make contacts 3', 313, 315, 311, 319,etc. of the relays individual to the various selector switches. Whenthis circuit is completed the all-busy relay of the master switch It.operates to prevent useless searching of the master switch for an idleselector switch. It will be understood from this explanation that whenone of the selector switches thereafter becomes idle, the associated oneof the relays R310, R312, R314, etc. is deenergized and restores to openthe chain operating circuit for the all-busy relay of the master switch.This relay, in restoring, permits the master switch to Search for theselector switch which has been released. Upon locating this selectorswitch the plungers of the idle line switches are all positionedoppositetheeontacts terminatingthe conductors of the trunk extending to the idleselector switch. I I

When the firstdigit 2 is dialed at the station A the cit-normal springsIfi3a of the signal transmitting device mm are opened to deenergize thelamp H350, for the durationof the dialing operaticn, and the pulsingsprin gs IEIZa are opened and closed twice to transmit two impulses overthe above-traced circuit for energizing the line relay B3). In thisregard, it will be noted that the current pulses are transmitted solelythrough the resistor Iiita. The relay R3Ill, upon restoring'at thebeginning of the open-circuit period of the first impulse, opens itscontacts 3I2 to interrupt the operatingand locking circuits for the tworelays R3 26 and R330. At its contacts BIS, the relay RSI?) completesthe prepared circuit for energizing the vertical magnet 364 in parallelwith the upper winding of the transfer relay R330. This circuit extendsfrom ground by Way of the contacts 340, 313, 3 23 and 332, and theparallel-connected windings of the relay R330 and the vertical magnet334 to battery. When energized over this circuit, the vertical magnet354, operating in conjunction with its associated ratchet and pawlmechanism, functions to move the wipers 350 to 353, inclusive, one stepin the vertical direction, wherein they are positioned opposite thefirst level of contacts in the associated contact field. When the wipersof the selector switch 12 are thus elevated to a position opposite anodd-numbered level of bank contacts, the normal post springs 305 aremoved into engagement to prepare a circuit for energizing the releaserelay R240. Incident to the vertical movement of the wiper carriagestructure, the vertical ofi-normal springs 351 are moved into engagementto complete the operating circuit for the trunk hunting relay R350; thevertical ofi-normal springs 369 are engaged to prepare the operatingcircuit for the release magnet 300; and the vertical ofi-normal springs368 are disengaged to deenergize the lower winding of the transfer relayR330. The purpose of energizing the upper winding of this transfer relayin parallel with the winding of the vertical magnet 354, during thedialing of the first digit,

now becomes apparent. Thus this parallel circuit provides a vehiclewhereby the transfer relay R330 is intermittently energized and therebymaintained in its operated position throughout the series of impulsestransmitted to the selector switch l2. Due to the slow-to-releasecharacteristics thereof, the relays R320 and R330 remain operated duringthe operation of the line relay R3 I0 to repeat the dialed impulses tothe vertical magnet 364, The circuit for energizing the trunk huntingrelay R350 extends from ground by way of the contacts 32l, 333 and 353,the ofi-normal springs 361 and the winding of R350 to battery. When thusenergized, the relay R350 locks to ground over a circuit including theoff-normal springs 35! and the contacts 353, 352 and 346. At itscontacts 35l, the relay R350 prepares the operating circuit for therotary magnet 355. When the second impulse is transmitted to the linerelay R3l0, the vertical magnet 364 is again energized and operates toelevate the wiper carriage structure a second step, so that the wipers350 to 353, inclusive, are positioned opposite the second level ofcontacts in the associated contact field. Incident to the movement ofthese wipers to a position opposite an even-numbered level of bankcontacts, the normal post springs 305 are disengaged to reopen theprepared point in the operating circuit for the release relay R240.Shortly following the end of the first digit, the transfer relay R330restores. In releasing, this relay opens its contacts 33l to interruptthe initially completed circuit for energizing the hold relay R320. Atits contacts 332, the relay R330 opens the above-traced circuit forenergizing its upper winding in parallel with the vertical magnet 364.thereby to prevent further impulses from being transmitted to thevertical magnet. At its contacts 333, the relay R330 opens thepreviously traced operating circuit for the trunk hunting relay R350. Atits contacts 334, the relay R330 completes the prepared operatingcircuit for the rotary magnet 365, this circuit extending from ground byway of the contacts 32l, 334 and 35!, and the winding of the magnet 355to battery.

Whenthe rotary magnet 365 is energized over the above-traced circuit, itoperates, in conjunction with its associated ratchet and pawl mechanism,to rotate the wipers 360 to 333, inclusive, into engagement with thecontacts forming the first contact set of the selected second level. Atits contacts 353, the magnet 365 opens the abovetraced locking circuitfor the trunk hunting relay R350. When thus deenergized, the relay R350restores and opens its contacts 351 to interrupt the operating circuitfor the rotary magnet 305. At its contacts 352, the relay R350 opensanother point in its own locking circuit. Further operation of themagnet 365 depends upon the idle or busy condition of the selected firsttrunk in the selected group, i. e. the trunk terminated at the first setof contacts in the selected contact level and extending to the firstconnector switch of the selected group. If this trunk is busy, theprivate or test conductor thereof is marked with ground potential and,accordingly, the trunk hunting relay R350 is reenergized over a circuitwhich includes the grounded wiper 351, the contacts 342 and 353, theofi-normal springs 361, and the winding of R350 to battery. Inreoperating, the trunk hunting relay R350 again locks to ground over apath including its contacts 352. At its contacts 35I, the relay R350recompletes the operating circuit for the rotary magnet 365. The magnet365, in reoperating, again deencrgizes the relay R350 and advances thewipers 300 to 363, inclusive, a second step, wherein they engage thecontacts terminating the conductors of the trunk extending to the secondconnector switch of the selected group. Ifthis connector switch is alsobusy the trunk hunting relay R350 reoperates to again close theoperating circuit for the rotary magnet 365, whereby the wipers 360 to363, inclusive, are advanced a third step to select the third connectorswitch of the group. This stepping operation on the part of the wipers330. to 333 continues until an idle connector switch of the group isfound or until all of the connector switches have been tested and foundto be busy.

During the trunk,hunting operation just described, the line switchingrelay R340 is shortcircuited until a trunk extending to an idleconnector switch is found, the path for short-circuiting this relayextending from the grounded test wiper 36i by way of the contacts 342,the winding of R340, the cam springs 304, and the contacts 321 back toground. Vihen, however, a trunk extending to an idle one of theconnector switches isfound, the test wiper 36l is disconnected fromground. When the short-circuiting path just traced is thus opened, therelay R340 is energized in series with the trunk hunting relay R350 overa circuit which extends from ground by way of thecontacts 32 l, the camsprings 304, the winding of R340, the contacts 353, the off-normalsprings 361 and the winding of R350 to battery. The winding of the relayR340 is of relatively high resistance as compared with the resistance ofthe winding of the relay R350. Accordingly,

. the current traversing the circuit just traced is insufficient tocause the reoperation of the trunk hunting relay R350. The relay R340,however, operates when energized in this circuit, and immediately opensits contacts 346 further to interrupt the above-traced locking circuitfor the trunk hunting relay R350. At its contacts 341, the relay R340opens another point in the operating circuit for the release magnet 356.At its contacts 348, the relay R340 further prepares the operatingcircuit for the timing relay R250. At

aasases 7 its contacts 342, the relay R340 opens the abovetraced circuitover which the trunk hunting: relay R350 is energized during the trunkhunting operati'on. At its contacts 343', the relay R340 connects thetest wiper 30! to the test conductor C! 35 of the selector switch I2,thereby to prepa-re alternative holding circuits for the magnet H0, andthe line relay R220. At itscontacts 344, the relay R340 opens theabove-traced operating circuit for the line relay R3I0. At its contacts340-, the relay R340 completes a circuit for energizing the pilot lampI05ain series with the line relay of the selected connector switch. Atits contacts 34!, the relay R340 completes a circuit for energizing thepulsing relay embodied in the selected connector switch.

Assuming that the-illustrated connector switch I3 is selected throughoperation of the selector switch I2 in the manner explained above, thepilot lamp l05a is energized in series with the line relay RAH! and thepulsing relay R440 is energized, incident to the operation of the lineswitching. relay R340. The circuit for energizing the line relay R4I0'may be traced as extending from ground by way of the pulsing springsI02a, the ofi-normal springs I03cr, the filament of the lamp I05a, thecontact springs. I48, the contact spring H9, CI34, the contacts 205 and242, G201, the contacts 345,.the wiper 362, C382, the contacts 464' andthe winding of R4III! to battery. when wenergized in this circuit, therelay R4I0 operates andcloses its contacts 4!! to complete a circuitthrough the ofi-normal springs 411 for energizing the'hold relay R420.At itscontacts 412, the relay R410 opens a point in the circuit fortransmitting impulses successively to the two magnets 414. and 415.

The relay R420, in operating, closes its contacts 423 to prepare thecommon portion of the pulsing. circuit for the twoenumerated magnets,and. locks to ground over a path including its contacts 422 and thecontacts 4II.. At its contacts 424-, the relay R420 preparestheoperating circuits for the transfer relays R450 and R450. At itscontacts 425, the relay R420 opens a point in the operating circuits forthe release mag.- nets 416 and 485'. At its contacts 42!, the relay R420completes the prepared alternative locking circuits for the magnet H andthe line relay R220,v these circuits commonly extending from ground byway of the contacts 42!, C38I-, the wiper 30!, and the contacts 343 tothe conductor C200 where they divide, one circuit extending through thecontacts 262. and the lower winding of R220 to battery, and the secondbranch exf tending by way of the contacts 24!, CI35, the contact springI20, thev contacts WI: and H5 in paralleLand the upper or BCO winding ofthe magnet H0 to battery. When ground potential is impressed upon thetest conductor C38! of the trunk I8 through operation of the hold relayR420, alocking circuit is also prepared for the supervisory relay R400,and the connector switch I3 is marked against seizure through any of theother selector switches having access thereto.

The above-mentioned circuit for energizing the: pulsing relay R440 maybe traced as extending from ground by Way of the contacts I94,

C535, the contacts 632, C505, the contacts 43!, the wiper 360', C330,and the winding of R440 to battery. When energized. in this circuit, therelay R440. opens its contacts 44 I and 442 further to interrupt theincomplete. circuits for transmiting current pulses to the operatingmagnetspf theindicatorswhich. are to be selected. At its contacts 443,the relay R440 opens a. point in. one of the. available circuits forenergizing the transfer control relay R430. Following the operationsjust described the connector switch I3 is conditimed to respond to theimpulses of the second digit of the identification number 241 assigned.

R220 and the line switching relay'R340. At its contacts 324', the relayR320'further prepares the operating circuit forthe release magnet 306.From this explanation it will be. understood that after the connectorswitch I3 is selected through the selector switch I2, only the lineswitching relay R340 is-operated in'the selector switch. This relay isheld energized in a circuit which may now be traced as extending fromground by way of the contacts42l, C38I, the wiper 30!, the contacts 343,thecam springs 3&4, the winding of R340, the contacts 353', theoff-normal springs 36'! and the winding of R350 to battery.

As indicated above, if all of the connector switches of the: selectedgroup are busy atthe time the searching operation of the selector switchI2 is initiated,'the rotary magnet 365 continues to operate until thewipers 360 to 363, inclusive, are stepped to the eleventh rotaryoffnormal' position thereof. Incident to the eleventh step of thesewipers, the cam springs 304 are disengaged to open a point in thepreviously traced operating circuit for the -line switching relay R340,and the cam springs 303 are moved into engagement to condition the busysignal relay R300 for control by the pulse generator 306. This generatoris arranged to transmit ground pulses 'over the pulsing lead 302 at arate of approximately I20 impulses per minute. Each time a ground pulseis transmitted over this lead, the busy signal relay-R300 winding of theline relay' R3I0 in the circuit for energizing the lamp I 05a at the endof each ground pulse transmitted over the lead 302 by the generator306.. The intermittent increase in the energization of. this lampresults in the production of a flickering signal, which serves to informthe calling doctor that the desired control connection cannot be set up.The manner in which the partially completed connection is released isexplained in detail hereinafter.

After the connector switch I3 has been seized through the selectorswitch I2, in the manner explained above, and when the second digit 4 ofthe doctors identification number 247 is dialed at the station A, theoff-normal springs I030. are again opened to exclude the pilot lampI05a' from the pulsing circuit, and the pulsing springs 3211 are openedand closed four times so that four impulses are transmitted to the linerelay R4I0. This relay functions to repeat the impulses to the transfercontrol relay R430 and thevertical magnet 4'14. Thus each: time therelay R4!!! restores it closes its contacts 452 to energize the relayR430 in a circuit including the contacts 464 and 423. At its contacts41!, the relay R410 opens the circuit for energizing the hold relayR420. At its contacts M2, the relay R4I0 also completes the circuit forenergizing the vertical magnet 474, this circuit extending from groundby way of the contacts M2, 454 and 423, the wiper 483 and the engagedfirst contacts of the contact sets 48! and 482, and the winding of themagnet 414 to battery. From'the above explanation it will be understoodthat the relay R420 operates at the beginning of the open-circuit periodof the first impulse transmitted to the line relay R4l0. Due to itsslow-to-release characteristic, this relay remains operated untilshortly after the train of four impulses is ended. Similarly, theslowacting hold relay R420 does not restore in response to theintermittent deenergization of its winding. In operating, the relay R430closes its contacts 43I to complete a circuit'including the contacts 424for energizing the slow-to-re lease relay R435. At its contacts 432,'therelay R430 opens a point in the operating circuit for the magnet 404.The relay R435, upon operating, closes its contacts 436 to prepare thelastmentioned circuit.

Each time the vertical magnet 474 is energized in the above-tracedpulsing circuit, it operates in conjunction with its associated ratchetand pawl mechanism to elevate the wiper carriage structure of theconnector switch l3 one step, so that at the end of the second digitdialed at the calling station A the wipers 41! to 413, inclusive, areleft standing opposite the fourth level of bank contacts in theassociated contact field. Incident to the first vertical step of thewiper carriage structure, the off-normal springs 418 are moved intoengagement to prepare the operating circuit for the release magnet 416;and the offnormal springs 47! are disengaged to interrupt the initiallycompleted circuit for energizing the hold relay R420. Shortly followingthe end of the second digit, and during the inter-digit pause betweenthis digit and the third or final digit the transfer control relay R430restores. In releasing, this relay opens its contacts 43I to interruptthe operating circuit for the relay R435. At its contacts 432, the relayR430 completes the prepared operating circuit for the magnet 484, thiscircuit extending from ground by way of the contacts 424, 432 and 436,and the winding of the ,magnet 484 to battery. When energized in thiscircuit, the magnet 484 operates to advance the wiper 483 one step fromits illustrated normal position. When this wiper is moved ofi normal,the above-traced operating circuit for the vertical magnet 414 isinterrupted and the operating circuit for the rotary magnet 415 iprepared. Shortly after the magnet 484 operates, the relay R435 restoresand opens its contacts 436 to deenergize the magnet 484. Incident to theoffnormal movement of the wiper 483, the off-normal springs 486 aremoved into engagement to prepare the operating circuit for the releasemagnet 485, and the oiT-normal springs 48! are disengaged to openanother point in the operating circuit for the release magnet 476.Following the operations just described, the connector switch I3 isconditioned to respond to the impulses of the third digit 7 of thecalling doctors in identification number.

When this digit is dialed at the station A, the pulsing springs l02a areopened and closed seven times so that seven impulses are transmitted tothe line relay R410. This relay, in following the impulses, functions totransmit a corresponding number of current pulses to the transfer relayR400 and the rotary magnet 475. The circuit for energizing the rotarymagnet 475 may now be traced as extending from ground by way of thecontacts M2, 454 and 423, the wiper 483 and the engaged second contactsof the contact sets 48! and 482, and the winding of the magnet 415 tobattery. Upon reoperating at the beginning of the third digit, the relayR430 recompletes the operating circuit for the relay R435. Thelastmentioned relay, in reoperating, functions to reprepare theoperating circuit for the magnet 484.

Each time the rotary magnet is energized in the above-traced pulsingcircuit, it operates in conjunction with its associated ratchet and pawlmechanism to rotate the wiper carriage structure of the connector switchl3 one step so that at the end of the third digit the wipers 4H to 413,inclusive, are left standing in engagement with the seventh contacts ofthe fourth contact level in the associated contact field. In thisposition of the wiper carriage structure, the enumerated wipersrespectively engage the contacts terminating the conductors C5l3, C5I4and C5l5 which extend to the indicators individual to the calling doctorNo. 247. At the end of the third digit dialed at the calling station A,the transfer control relays R430 and R435 restore in sequence totransmit a second current pulse to the operating magnet 484 of the minorswitch 480. In reoperating, the magnet 484 advances the wiper 483 asecond step wherein the respective third contacts of the two contactsets MI and 482 are bridged by this wiper. Immediately the wiper 483 isstepped to this position, a circuit is completed for energizing thelower winding of the relay R460 and the upper winding of the relay R450in parallel. This circuit extends from ground by way of the contacts424, the wiper 483 and the engaged third contacts of the two contactsets MM and 482, and the parallel-connected windings of the two relaysR450 and R460 to battery. When thus energized, the relay R460 closes itscontacts 45| further to prepare the circuit for transmitting currentpulses to the operating magnet 50Ib of the indicator 5001). At itscontacts 463, the relay R400 prepares a circuit for transmitting a firstreset pulse to the magnets 50 lb of the indicator 5001). At its contacts464, the relay R460 opens another point in the previously tracedcircuits for energizing the relay R430, the vertical magnet 414 and therotary magnet 415. At its contacts 455, the relay R460 opens anotherpoint in the incomplete operating circuit for the release magnet 485. Atits contacts 400, the relay R460 further prepares the operating circuitfor the timing relay R250.

The relay R450, upon operating, closes its contacts 45! to prepare acircuit for transmitting current pulses to the operating magnet 50la ofthe indicator 500a. At its contacts 454, the relay R450 opens a point inan alternative circuit for energizing the transfer relay R460. At itscontacts 455, the relay R450 opens another point in the incompleteoperating circuit for the release magnet 485. A1; its contacts 456, therelay R450 further prepares the operating circuit for the timing relayR250. At its contacts 45l, the relay R450 also completes a circuit forenergizing the relay R400. The character of this circuit depends uponthe positions occupied by the selected indicators. If any one of theseindicators occupies an cit-normal position, the contact springs 502thereof are engaged and the contact springs '503 are disengaged.Assuming, by way of example, that the tens indicators of the selecteddisplay units occupy positionswherein they respectively display thenumber 5, so that the "contact springs 502a of the indicator 50041, forexample, are engaged, the circuit for energizing the super visory relayR000 may be traced as extending from ground by way of the springs 502a;the winding of the magnet 501a, C5l4, the wiper 012, the Contacts 45|and 403, and the lower winding of R400 to battery. The currenttraversing this circuit and the parallel branches thereof which extendthrough the windings of the selected other tens indicators, isinsufficient to cause the operation of thes indicators. If all of theselected indicators occupy their respective normal or blank-positions,the circuit for energizing the relay R400 is completed by the transferrelay R460 and extends from ground by way of the contacts 401 and 463,the wiper 413, G595, the contact springs 502a, etc., theparallelconnected windings of the operating magnets in the selected tensindicators, C5I4, thewip'er 412, the contacts 45l and 403, and thelowerwindin'g of R40 to battery.

When energized over either of the above-traced circuits, the relay R400locks to ground over a path including its preliminary make contacts 402and the contacts 42L At its contacts '40ll' the relay R400 thendisconnects the start conductor C5 5 from ground. At its contacts'403,the relay R000 opens a point in its operating circuit as traced above.At its contacts 406, the relay R400 completes the above-mentionedoperating circuit for the timing relay R250, this circuit extending fromground by way of the contacts 466; 456 and C383, the wiper 363, thecontacts 348, CH8, the contacts 222 and the winding of R250 to battery.At its contacts 405, the. relay R400 prepares an alternative operatingcircuit for the transfer control relay R430. At its contacts 404, therelay R400 opens the path normally shortcir'cuiting the resistor 40!,whereby this resistor is serially included in the circuit over whichtherelay R490 and the pilot lamp la are energized. The current traversingthe pilot lamp l05a'is thus decreased. with a resulting decrease in theillumination of this lamp. This decrease in the light transmitted by thelamp 105a serves to inform the calling doctor that the desiredindicators have been selected. At this point it may be noted that, afterthe two transfer relays R450 and R460 and the supervisory relay R400operate, the control of the switching equipment is transferred from thecalling control station A to the automatic pulsesender I5. It willfurther be apparent that no additional operations are required on thepart of the calling doctor' in order to cause the selected indicators tobe reset to display a numerical indication of the'floor" on which thedoctor No. 247 is located. 'Ihecontinued energization of the pilot lampI05a, however, serves to indicate the busy condition of the controlstation A from which the control connection was routed to the desiredindicator.

When energized over the above-traced circuit, the relay R250 opens itscontacts'253-further to interrupt the incomplete operating circuit'forthe release relay R230. At its contacts 254, the relay R250 opens apoint in the-prepared locking circuits for the tworelay R230 and-R240.The relay R250 is equipped with a weighted vibratory contact 5 ring 25I, which is set in vibration when the armature controlled by this relayis' attracted.

So longas vibration of this weighted contact spring continues, thecontacts 252 areonly intermittently engaged for short time intervals.After a predetermined period elapses, however, the vibration of thecontact spring 251 is arrested '50 that the contacts 252 remain closed.When this occurs, the relay R260 is energized in an obvious circuit and,accordingly, operates aftera short interval. The purpose of delaying theoperation of the start sending relay R260 for a short time intervalafter the indicators have been selected and in the manner justdescribed, is to permit the control connection to be released in the"event the calling doctor discovers that he has dialed the wrongidentificationnumber. This. prevents the settings of the erroneouslyselected indicators from being disturbed. I

In operating, the start'sending relay R260 close its contacts 269 tocomplete a multiple path for impressing ground potential'upon-the timerstart lead C226. At itscontacts 268, the

, relay R260. prepares multiple locking circuits for the two relays R230and R240. At its contacts 265"the relay R260 prepares an alternativeoperating circuitfor the release relay R230. At its contacts 264, therelay R260 completes an alternative circuit for energizing the linerelay R4|0 of the operated connector switch it, thi 'circuit extendingfrom" ground by way of the contacts 26.4 and242, C201, the' contacts345, thewiper 362, C382, theresistor 401 and the Winding'of R4l0 tobattery. After-this circuit is completed,

the-relay R260 opens its contacts 265 to interrupt the above-tracedcircuit for energizing the line relay R4I0- in series'with the pilotlamp I05a. At its contacts 263, the relay R260 completes a circuit foritenergizing the pilot lamp I050. in se ries with the upper winding ofthe line relay R220, this circuit extending from ground by way of ,the'pulsing'springs l02a, the shunt springs l03a,"the"filamentof the lampI05a, the contact springs I08, the contactspring I I9; C l 34, thecontacts 263, and the upperwinding of R220 to battery; The upper windingof the relay 'R220is of I relatively: low resistance. Accordingly, "thepilot lamp w is more brilliantly illuminated when this winding issubstituted forthe winding of thelinerelay R410 in-the circuit forenergizing the pilot lamp l05a. This increase in the intensityof'thesignal serves to inform the calling doctor that the resetting ofthe selected indicators is about to be started.

At its contacts ZELthe relay R260'completes a multiple path'includingthe contacts 252 for impressing ground potential upon the connected testconductors CH5 and CSBI; therebyto provide'multiple locking circuitsforthe relays R340 andR400, and the magnet H0. At its contacts 261, therelay R260 also completes a locking circuit for itself, this circuitextending lfrom ground by way of the contacts 42!, 038i, thewiper .361,the contacts 343, C200, the contacts 26!, and the winding of R260 tobattery. After the contacts 26! are closed, the relay R260 opens itscontacts 262 to deenergize the" lower winding of the line relay R220.

The energization of the upper winding of the relay 22s in series withthe pilot ia fme isinsufficient to maintain-this relay in its operatedposition. Accordingly. when the circuit for energizing the lower windingof the relay R220 is opened'at'the contacts 262, thisrelay restores andopens its contacts 22! further'to interrupt oneof the incompleteoperating circuits for the release relayR230." At its contacts 222,'the-r'elay R220 opens the above-traced operating circuit for the relayR250. At its contacts 224, the relay R220 opens a point in the initiallypreparedlock- .ing circuits for the two relays R230 and R2,l0. At itscontacts 225, the relay R220 opens one of the multiple paths over whichthe timer start lead CZZS is connected to ground. At its contacts 223,the relay R220 prepares the operating circuit-for the release relayR240.

The relay R250, upon restoring, opens its contacts'252 to interrupt theoperating circuit for the relay R260 and the above-traced multiple pathfor impressing ground potential upon the connected test conductors C381and C135; At its contacts 253, the relay R250 further prepares theabove-mentioned alternative operating circuit for the release relayR236. At, its contacts 254, the relay R250 repreparesthe lockingcircuits for the two relays R230 and R240.

The startsending relay R260, upon operating, alsojnitiates the operationof theautomaticpulse sender ,15. Thus, when this relayrcloses itscontacts 266, a circuit including the conductor C2.1;4 and the contacts662 is completed for energizing thelower winding of the start relayR050. At its contacts 267, the relay R260 also completes .a circuit forenergizing the slow-acting holding relay R600, this circuit extendingfrom ground by way of the contacts 283, .267 and 26.4, .C6|;5 andthewinding of R680 to battery. The relay R650, upon operating, closes itscontacts 051 to prepare operating and locking circuits for thereleaserelay R640. At its contacts652, the relay R650 prepares theoperating and locking circuits for the digit spacing control relays R790,and R600. At its contacts 653, the relay R650 .prepares a circuit forinitiating theoperationof the three pulse generating relays R6i0, R615and R620. At its contacts 654, the relay R650 prepares the operating andlocking circuitsfor certain of the relays in the pulsecounting network31. The relay R660, .upon operating, opens' its contacts 682 tointerrupt the path normally short-circuiting the upper winding of thestart relay R650, thereby to permit the two windings of the latter relayto be energized in series over ,a circuit including the groundedconductor C214. At its contacts 681, the relay R680 completes an obviouscircuit forTenergizing the relay R660.

The relay R660, upon operating, closes its con- .tacts 661 to completetheprepared operating circuit for the slow-to-releaserelayR620, thiscircuit extending from ground by way of the contacts 654 and 668, G673,the contacts 767, C674, the contacts 66!, C671, the contacts 786, C670,the contacts 653 and 616, and the winding of R620 to battery; Thus theoperation of the three pulse generating relays R610, R615 and R620 isinitiated. More specifically, the relay R620, upon operating, locks upin a circuit including its contacts 623 and 0118 001108005 616, andcloses its contacts 621 to complete an obvious circuit for energizingthe relayR630. At its contacts 622, the relay R620 prepares alockingcircuit for the stop relay R760. The relay R630, upon operating,closes its contacts .631 to .complete an obvious circuit for energizingthe relay, R6l5. The relay R655 now operates and opens its-contacts 616to deenergize the relay R620, whereby the three relays R620, R630 andR615 are caused to release inthe order named, and inan obvious manner.The relay R615, upon-restoring, closes its contacts 616 to recompletethe operating circuit for the relay R620. Thus a second cycle of the.grpundedlead C674, the the contacts 702, and the upper winding of R700to battery.

operation Tof the three pulse generating relays is initiated.

;'I -he.operating cycles of the three pulse generatin'g relays arecounted through operation of the relays in the network 3|. Thus when therelay R630 first operates, a circuit is completed for energizing'thefirst counting relay R710, this circuit extending from ground by way ofthe contacts 654 and 6,08, C673, the contacts 797, G674, the contacts636, C668, the contacts 725, 756, 746, 73 6, 726 and 716, and thewinding of R710 to battery. In operating, the relay R660 also functionsto complete a path for short-cirouiting the lower winding of thetransfer relay R700, this path-extending from the conductor C674 by-wayof the lower winding of R700, the ,contaots'70L-C690-and the contacts630 back to the ,conductor C674.

When energized in the above-traced circuit, the relay R7 10 locks toground over a path including the contacts H3 and 723, the lower.winding-qf-R'lllfl, the contacts 797, G673, and the contacts 608 (and654. At its contacts H1 and 71 2, the-relay R7I0 prepares twoalternative circuits "which respectively include the first and sixthmarking leads over which the stop relay R700-may'be energized in themanner pointed out below. At .its contacts 7M, the relay R710 preparesthe operating circuit for the second co11nfing.-r elay R720. At itscontacts 716, the relay R710 opens a point in its own operating circuit..At itscontacts 715, the relay R716 completes an alternative lockingcircuit for itself, this alter native circuitextending from ground bywayof the-contacts 654 and 608, C673, the con tacts 7; 97, 667,4,thecontacts 633, C608, the con- :tacts i795, 704' and 115, and the windingof R710 to :batter-y.

As the first cycle of operation of the three pulse generating relaysprogresses, the relay R630 restores to-interrupt theoperating circuitfor the relay R7 1,0-and the path short-circuiting the lower winding ofthe transfer relay R706. At this time the 'lower winding of the transferrelay is energized inseries with the relay R710 over a circuit whichextends by way of the grounded lead (167.4, the lower winding of R760,the con-- tacts 723 and 7,13, and the winding of R710 to battery. ffhecurrent traversing this circuit is sufficientto maintain the relay R716in its operat edposition and to cause the operationof the relay ;R7 0 0.In operating, the relay R700 closes its contacts .702 to prepare analternative looking circuit -for itself. At its contacts 704, the

- relay R700 vopens one of the above-traced and now incomplete lockingcircuits for the relay -R7-1,0. At-its contacts 703, the relay R700further prepares '-;the operating circuit for the second counting relayR720.

When the relay R636 operates during the second cycle of operation of thethree pulse generating relays R615, R620 and R630, the operating circuitfor thesecond counting relay R720 is completed. flfliis operatingcircuit may now be traced as extending by way of the grounded lead C674,the contacts 633, 0698, the contacts 765, 703 and 714,- andthe'windingof R720 to battery. In operating he second-time,-the relayR660 also completes the prepared locking circuit for the trans- .ferrelay R700, this circuit extending by Way of contacts 634, C699,

{I'he relayiR720, upon operating, locks toground ovena ,-path-includingthe contacts 724 and 733,

and the grounded conductor C614. At its contacts 125, the relay R120prepares the operating circuit for the third 'counting relay R130, Atits contacts 12%, the relay R120 opensanot'her point in the above-tracedoperating circuit forthe'relay R1I0. At its contacts 123, the relay R120opens the established locking circuit for the relay R110, causing thelatter relay to restore. At its contacts 121 and 122, the relay R120prepares two alternative circuits, which respectively include'the secondand fifth marking leads, over which the stop relay R180 may beenergized. The relay R1l0, upon restoring, opens its contacts 153further to interrupt its locking circuit and the circuit for energizingthe lower winding of the transfer relay R100. At its contacts N4, therelay R115 interrupts the operating circuit for the relay R120. At itscontacts 1H5, therelay RM reprepares its own operating circuit. At itscontacts 12! and H2, the relay R1l0 opens the prepared circuits,including the first and sixth stop relay R130- marking leads, over whichthe may be energized. I H

When the relay R630 restores during the second operating cycle of thepulse generating relays, the above-tracedlocking circuit for thetransfer relay R100 is opened at the contacts 634. The relay R1130accordingly restores and closes its contacts 104 furtherto prepare theoperating circuit for the third counting relay R130. At its contacts103, the relay R100 opens" another point in the operating circuit forthe second counting relay R120. At its contacts 102, the

relay R160 further interrupts its, own locking circuit. At its contacts104, therelayR100 reprethe path for short-circuiting its lower wind:

pares ing.

operating cycle of the pulse generating relays, the third counting relayR133 is energized in its operating circuit, which may now be traced asextending byway of the grounded lead C614, the contacts 033, C098, thecontacts 105, 104 and 125, and the winding of R130 to battery.In'operating the third time, the relay R630. also closes its contacts634 to recornpletethe previously traced path for short-circuiting thelower winding of the transfer relay R100.

In operating, the relay R130 locks to the grounded lead 0614 over a pathincluding the contacts 134 and 143, and the lower winding of R100. Atits contacts 135, the relay. R130 prepares the operating circuit for thefourth counting relay R140. At its contacts 136, the relay R130 opensanother point in the previously traced operating circuit for the relayR110." At its contacts 13l and 132,. the relay R130 prepares .circuits,which respectively include the third and eighth marking leads, overwhich thefstop relay R180 may be energized. At its contacts 133, therelay R130 interrupts the locking circuitfor the relay R120 causing thelatter relay to restore'j In releasing, the relay R120 opens itscontacts 124. further to interrupt its own locking circuit, closes itscontacts 123to reprepare the locking circuit for the first countingrelay R1l0, and closes its When the relay RG operates during the thirdof the transfer relay R100 are interrupted at the contacts 633 and 634,respectively. Incident to this operation, the lower winding of the relayR100 is energized in series with the third counting relay R130, over acircuit which include the grounded conductor C614, and the contacts 143and 134. In reoperating, the relay R100 again closes its contacts 102toreprepare its own looking circuit, andcloses' its contacts 103 furtherto prepare the operating circuit for thepfourt counting relay R140.

1 When the relay R630 operates during the fourth operating cycle of thethree pulse generating relays, itrecloses its contacts 634 to againcomplete the locking circuit for the transfer relay R100, and closes itscontacts 633 to complete the prepared operating circuit for the fourthcounting relay R140. Ifhe latter circuit may now be traced as extendingfrom the grounded lead C614 by way of the contacts 533, C698, thecontacts 105, 103; and 135, and the winding of R140 to battery. 'Inoperating, the-relay R140 locks to the grounded lead C614 over a pathincluding the contacts 144 and 153, and closes its contacts 145 toprepare the operating circuit for the fifth countingrelay R150. At itscontacts 146, the relay R140 opens another point in the incompleteoperating circuit for the first countingrelay R110. 'At its contacts 14|and 142, the relay R140 prepares two alternative circuits, whichrespectively include the fourth and ninth marking leads,'over 'whichthestop relay R180 may be energized. At its contacts143, the relay R14llinterruptsthe circuit over which the relay R130 is energized in serieswith the lower winding of the relay R100. When this circuit is broken,

I the relay R130 restores. In releasing, the relay contacts 126 furtherto prepare the previously R opens its-contacts' to interrupt theoperating circuit forthe relay R140, closes its contacts 136 further toprepare the operating circuit for the relay-R110, and closes itscontacts 133 to reprepare the locking circuit for the relayR'n'ZB; Atits contacts 134, the relay R130 opens another point in its own lockingcircuit. At its contacts 13! and 132, the relay R130 opens the prepared'circuits, which respectively include the third and'eig'hth markingleads, over which the stop relay'R180 may be energized. When the relayR630 restores during the fourth operating cycle of the threepulsegenerating relays, the locking circuit for the transfer relay R100 isopened at the c'ontacts 634. The last-mentioned relay now restores andcloses its contacts 104 further to prepare the operating circuit for thefifth countingrelay R150.

When therelay Rfiiifioperates during the fifth operating cycle of thethree pulse generating relays, the contacts 533 are reclosed to completethe prepared operating circuit for the fifth counting relay R155, "thiscircuit extending from the grounded lead C514 by way of the contacts633,

C308, the contacts 195, 104 and and the winding ofR to battery. Inoperatingjthe relay R15fi locks to the grounded lead C514 over includingthe fifth markingzlead over which the stop relay'R130maybe energized. Atits contacts.152, the relay R150 prepares'anobvious alternative circuitforenergizing the stop relay.

the above-traced locking circuit for the fourth counting relay R140. Thelatter relay now restores and opens its contacts .145 to interrupt theoperating circuit for the relay R150. At its contacts 144, the relayR140 Opens another point in its own locking circuit. At its contacts143, the relay R140 reprepares the locking circuit for the relay R130.At its contacts 146, the relay R140 reprepares the operating circuit forthe relay R1l0. At its contacts 161 and 142, the relay R140 opens thetwo prepared circuits, including the fourth and ninth marking leads,over which the stop .relay R180 may be energized.

The relay R150, upon operatingclcses its contacts to complete anobvicuspath for shortclreuiting the-winding of the transferrelay R110.Shortly following the operation of the relay R160, and during thecontinued operation of the three Lpulse generating relays, the relayR630 restores and opens its contacts 633 to interrupt the lockin circuitfor the fifth counting relay R150. In releasing, the relay R150 opensits contacts 151 and 152 to interrupt the prepared operating circuitsfor the stop'relay R130, and closes its contacts 153 to reprepare thelocking circuit for the fourth counting relay R140. At its contacts 155,the relay R150 opens another point in its own locking circuit. At itscontacts 156, the relay R150 prepares another point in the operatingcircuit for the first counting relay R110. At its contacts 154, therelay R150 opens the path shcrt-circuiting the winding of the transferrelay R110, permitting this winding to be energized in series wtih thewinding of the relay R160 over .a circuit which includes the groundedconductor C614 and the contacts 161. The current traversing this circuitis sufficient to maintain the reflexing relay R160 operated and to causethe operation of the transfer relay R110. In operating, the latter relaycloses its contacts 112' to prepare'the five circuits which respectivelyinclude the sixth to ninth marking leads, and the contacts 152, forenergizing the stop relay R100. At its contacts 11], the relay R opens apoint in the common portion of the five circuits, which respectivelyinclude the first to fifth marking leads, and over which the stop relayR180 may be energized.

Following the operation of the transfer relay R110, and during thecontinued operation of the three pulse generating relays, the transferrelay R100 coacts with the five counting relays to count the sixth totenth impulses of the pulse train under consideration. The manner inwhich these relays respond to the sixth to tenth operating cycles of thepulse generating relays is exactly the same as just described withreference to the counting of the first to fifth impulses.

When the fifth counting relay R operates the second time to count thetenth cycle of operation of the three pulse generating relays, it closesits contacts 152 to complete a circuit through the contacts 112 forenergizing the stop relay R180. In operating, the relay R180 locks toground over a path including the contacts 182, C688, and the contacts622 of the operated pulse generatingrelay R620. At its contacts 18I, therelay R180 completes a path including the conductor C680, and thecontacts GM, and GM, for impressing ground potential upon the transferlead C208, for a purpose to be described hereinafter. At its contacts183, the relay R180 completes the prepared operating circuit for therelay R190, this circuit extending from ground by way ;of thecontacts-652, @689, the contacts 183, (3695, the contacts 4505, C003andthe winding of R190 ,to battery. ,At its contacts 184, the relay R180opens :a point in an incomplete locking circuit for the two relays R190and R600. At its contacts '18 5, the relay R180 opens a point in theoperating circuit for-the relay R600. At its contacts 186, the relayR180 interrupts the previously traced operating circuit for the relayR520.

Therelay R190, upon operating, closesits contacts 191 to complete amultiple circuit including the-conductor C690 for energizing the relayR060. At its contacts 192, the relay R190 prepares a locking circuit foritself and the relay R000. At its contacts .193, the relay R190 preparesthe operating circuit :for the relay R000. At its contacts .194, therelay R190 opens the path'normally short-circuiting the winding of therelay R6l0, whereby :this winding is included in the previously tracedoperating circuit for the pulsing relay R440. At its contacts 195, therelay R190 opens a point in the common portion of the previously tracedoperating circuits for the live counting relays of the counting network3|. Atits contacts 191, the relay R190 disconnects the pulsing andlocking lead C614 from ground. At its contacts 196, therelay R190prepares an alternative path gisrmimpressing ground potential upon thelead When the relay R190 operates, in the ,manner just described, todisconnect the leadC614 from ground and to interrupt the operating andlocking circuits for the fifth counting relay R150, this relay and thetwo relays R and R110 restore. Thus the relays of the counting network3| are all released. When the above-traced path shortcircuiting theWinding of the relay R610 is opened at the contacts 194, to includethe-winding of the relay R610 in-thecircuit for energizing-the pulsingrelay R440, the relay R6l0 operates and closes ltSCOI'ltZLCtSB.toprepare an obvious alternative circuit for transmittingcurrent pulsesto the five counting relays of the network 3|. This circuit is utilized.to control the operation of the counting relays during the spacinginterval which separates the impulses of the first impulse train, justconsidered, from the impulses of the second train. In this regard, it ispointed out that the counting relays as controlled by the three pulsegenerating relays are utilized to measure the inter-digit pause betweensuccessive digits or impulse trains. During the final portion of thetenth operatmg cycle ofthe three pulse generating relays, the relay R620restores and opens its contacts 022 to mterrupt the above-traced lockingcircuit for the stop relay R180. The relay R now restores and opens itscontacts 18l to disconnect the transfer lead C208 from ground. At itscontacts 182, the relay R180 opens another point in its own lockingcircuit. At its contacts 186, the relay R180 reprepares the operatingcircuit for the pulse generating relay R020. At its contacts 185, therelay R180 completes .the prepared operatmg circuit for the relay R600,this circuit extending from ground .by way of the-contacts 652, C669,thecontacts and 193, C694 and the lower winding of R600 to battery. Atits contacts 184, the relay R180 completes a circuit for energizing theupper winding of the relay R600 in series with the relay R190, thiscircuit extending from ground by way of the contacts 652, C689, thecontacts 184, C69], the upper winding of R60 0,'C092, the contacts'192and the Wi of R to battery. After the last-mentioned circuit iscompleted, the relay R180 opens its contacts 783 to interrupt theoperating circuit for the relay R190.

The relay R800, upon operating, opens its-contacts 605 further tointerrupt the operating circuit for the relay R190, and closes itscontacts 604 to prepare alocking circuit for itself. At its contactsBill, the relay R660 opens another point in the above-traced path forimpressing ground potential upon the transfer lead C208. At its contacts602, the relay R600 prepares a circuit which terval. At its contacts608, the relay R690 opens another paint in the initially traced path forirne pressing ground potential upon the pulsing and locking lead C57 3.At its contacts 601, therelay REM connects the lead C614 to ground, overan alternative path which includes the contacts 796, C612, and thecontacts 654.

Following the operation of the relay Rfi fldfthe three pulse generatingrelays, operating in contacts, 436; ,when the, relay R435 I recperates;Due

, to the slow-to-release characteristics thereof, the

v20 to thepulsing relay RM!) during the spacing inrelays :R430and R435remain intheir-respective operated; positions until shortly afterthefrestpr- .ing pulse trainisended.=, Y a a Each time a current pulseis transmitted throughoperationof the pulsing relay R440 to theoperatingmagnet 501cm; the indicator 50M, for example, ,the drum of thisindicator is advanced one step, towards its normal or blank position,-Thedisplay, drums of the other indicators arecorrespondingly operated inresponse to the operation of the pulsing relayRt lfi. .Inthisregard;:it: is ,again. pointed out that when the display drurnoi any indicator580 oc'cupiesdts nor,- mal or blan-k position, the associated cam 534'c? cupies a position such that the commutating springs 583 are engagedand the springst2 are disengaged. In all other positions of the displaydrum, the commutating,springsfilllare engaged. Accordingly, if theindicating drum offthe regisj ter, 560a, for example-, is assumed tooccupyits second off-normal position at the time the operation of thepulsing relay R4450 is initiated, nine junction with the relays of thecounting network 3!, function to measure the inter digit spacinginterval. In this regard it will be noted that the automatic pulsesender has, at this time, completed its operation to produce tenimpulses.

These impulses are repeated by the relay, R630 of theseindicators totheir respective normal'or;

blank positions. Thus each time the relay R440 restores, it closes itscontacts 442 to completethe prepared circuit for energizing theoperating magnet sum of the tens indicatorBililwgthis'circuit extendingfrom ground by way ,of the-c0n-;

tact springs 5ll2a,-the winding of the magnet 5cm, 05M, the wiper 412,the contacts land M2,-and the resistor ME-to battery, Similarly, acircuit is completed for energizing'the.,- operating magnet H) of theunitsiindicator 500beach time the relay RM!) restores, this circuitextending from ground by way of the contact, springs 5921), the windingof the magnet 501b, C513,,the wiper ill, the contacts 46! and 4M, andthe resistor M4 to battery. When the pulsing relay R440 initiallyrestores at the beginning of the restoring pulse train, the preparedalternative circuitior energizing the transfer controlrelay R430 iscompleted, this circuite tending from ground by way of the contacts 505,4 43 and 423, and the winding of R430 to battery. In reoperating, therelay R430 recompletes the operating circuit for the relay R435, andopens a point in the operating circuit for the magnet 484, Thisoperating circuit is further prepared at the con- The pulsing relay R440functions to repeat the V -restoringpulses transmitted by the relayR5159 of the ten, restoring pulses willbe, transmitted to the magnet50in. At ,the,;-,end of theninth step the cam 504w operates to epenjthecommutating contact springs 5il2cggand to close'f the springs 503a,;thereby to prevent thelr'erna'ining restoring pulse 0f, the trainiromproducing further operation-of, the magnet {it {a In'amanner imilarto thatjustdescribecl, a portion or all of the .to' the magnet; 50H) ofthe units indicatorf5ilub maybeutilized to drive the drum of thisindicator back-to its normaior blanlfrposition. "Thus if the indicatingdrum of theregister 50tbqoc cupies; its fifth cit-normal position, forexample, (at the time the operation soi the I relay' IRd lil isinitiated, sir; of the restoring; pulses will be utilizedto"advance:ythis-drum to its normal or blank position It-,,will beunderstood from: the ,aboye explanation that after a maximum often're'lstoring pulses,- have been trans'rnitted thr cjugh operation of:the relayRMiJ to the operating mag K .nets of ,the elected indicators,all of the display drums of the selected indicators are re- :s'toredtotheir=norrnalor blank positions. l

1. After ten restoring pulses have been counted "by-the automatic" pulsesenders! 5, the relay R590 closes its contacts-B06, to shunt the pulsingcon tacts .632, 501 that the pulsing relay Rfl iil is held in its:operated position. Accordingly,v the two -re1ays R430 and'R i35'arecaused sequentiallyto restore, in the manner previously described, :totransmit a current pulse to the operatingmagnet- 484 of the minor switchace. The. resulting operationof this magnet causes the .wipei' 633 -'to'be advance'd'out of engagement with its associated third contacts, andinto engagement with its associated fourth contacts. With the wiper 433in thi -positi0n, the-re1ay Refill is'deener- 'gized-and' an alternativecircuit is'completed for energizing the relay R ltll. This alternativecircuitext'ends from groundby' wayof the con- "ta'ct'sfl l, thefwiper3B3 and'the engaged fourth contacts ofthetwocontact sets 481 andllBZ,and

the lower winding otRtilO to battery. The relay R460, in", releasing,bpensits, contacts its rurthere to interrupt the initially 7 completedpat h Oval which ground potential was impressedupo'n the start.conductor G5 I 5'; At its contacts 462, the

relay R460 connects this conductor to ground throu ghthe contacts l,53of the operated} relay

